Method of recessing wire coils



Siam 19%. g o. HAAS 2,385,357

M'rTZTHOD OF RECESSING WIRE COILS Filed April 26, 1944 .2; i 1:: K/ R. 0 r w HA A 5 BY 5 1 m;;;\,

Patented Sept. 25, 1945 n UNlTED STATES PATENT orrics I METHOD maxilla wra COILS Otto Haas,

Richmond Hill, N. Y., Aircraft Screw Products Company,

assignor to Inc., Long Island City, N. Y., a corporation of New York Application April 26, 1944, Serial No. 532,717

9 Claims.

The present invention relates to wire coils of the type described in my co-pending application Serial Number 514,438, filed December 16, 1943, of which this is a continuation in part.

For certain uses of wire coils, e. g. such which are employed as thread inserts for screw connections, it is necessary to. contract the coil by atorque applied to at least a portion thereof between one of its ends and its body before the coil can be placed in position for the job for which it is destined. This requires the formation of some means in, connection with one of the end convolutions to serve as a grip for a tool whereby the contracting force can be applied to the coil. Furthermore, positioning of thecoil according to its destination'no portions thereof project from the contours of the uniform wire helix. For this purpose, according to the invention disclosed in my abovementioned application, a recess or notch may be provided on the inside of an end convolution of the coil, so that the ultimate end of the coil is shaped like .a hook which may be engaged by a tool. Other coil forms for similar purposes require the provision of a notch on the inside arch the outside of an end convolution in order to facilitate, after the positioning of the coil, the breaking of a tang or other end portion provided merely for the application of a tool.

Particularly if the coil is of the cylindrical type and wound without gaps or onl small gaps between adjacent convolutions, working of recesses or notches into the end convolution in a conventional manner is a rather intricate job, or at least one calling for great care in order to prevent injuries to the subsequent convolution. It is, therefore, an object of the present invention to provide a method facilitating the notching or recessing of an end convolution of a coil while safeguarding the subsequent convolutions against an unintentional contact with the notching tool. The invention mainly consists in that the convolution or the arc portion of the convolution to be notched or recessed is first shifted in substantially axial or radial direction in relation to the remainder of the coil, so that there is a clearance between the portion to be notched and other portions of the coil. While the portions are held in such relative positions, the desired notch or recess may be applied whereupon the dislocated portion is returned or permtted to return to its initial position.

Further objects and details of the invention will be apparent from the description given hereinafter and the accompanying drawing diagramit is necessary that after the 7 while the latter is 'matically illustrating two way of application of the method according to the invention.

In the drawing, a

Fig. 1 is a perspective view. of a coil with a recess produced by the method according to the invention;

Figs. 2 and 3 are diagrammatic top view and cross-section respectively, of a coil in which one end convolution is shiftedin a radial direction for the recessing operation; and

Fig. 4 is a diagrammatic view of a coil in which one end convolution is shifted in an axial direction for the same purpose.

Referring now to the drawing, Fig. 1 illustrates a cylindrical coil I wound of a wire with diamondshaped cross-section. The end convolution 2 is provided with a recess or notch 3 on one of its peripheral sides, which in the illustrated example is the inside of the coil. The recess extends to approximately cross-section. It will be clear from Fig. 1, that very great care must be taken and that still the danger of injuring the subsequent convolution l prevails if the recess is worked into the originally uniform cross-sections of the end convolution in its illustrated position relatively to the convolution l. Particularly if the path of the recessing tool is in a substantially axial direction, the tool must be stopped exactly after the completion of the recess if otherwise it is to be prevented from penetrating into the convolution 4. This is extremely difficult to accomplish if a clean-cut of the recess is desired.

Now, in order to avoid such difllculties, I shift the first convolution 2 or only an arc portion of such convolution, as much as may be required, in relation to the remainder of the coil, so that the recessing tool has a path clear through the wire thickness without hitting the subsequent convolution 4. This can be accomplished in the manner illustrated in Figs. 2 and 3, where the coil l is placed on an inner bottom projection 8 of a stationary member 5 which has an approximately semi-cylindrical side wall I according to the outer diameter of the coil." Thus, the coil is supported from below and the side to an extent of approximately half its circumference while an arc portion 8 of the upper end convolution is positioned opposite the wall I.

Another member 9 is formed and recessed in its front face at l0 according to the shape into which'it is intended to bend the arc portion 8. By moving member 9 in the direction of the arrows a the arc portion 8 will be bent inward into the position shown in Figs. 2 and 3 where the arc half the thickness of the wire portion 8 projects inwardly in relation to the coil body. Another member H may be inserted into the coil from below so as to support the lower face of the arc portion 8. Member I I is recessed at l2 in the area underneath the arc portion where the recess 3 is to be provided. Now, a tool 13 may be applied from the top and moved in the direction of the arrow b to produce the recess 3 in a cutting, punching or other suitable operation, and it will be apparent that the tool l3 can be advanced as deeply into the coil as desired and as permitted by the depth of the recess l2 Without interfering with any other portion of the coil. When the recess 3 has been formed tool l3 may be lifted into the position of Fig. 3 whereupon members 9 and II may be withdrawn towards the left and downward respectively so that the recessed coil can be lifted from the support 5. Depending on the material of the coil wire the recessed end convolution will either spring back into its original position or it will stay in the form of Figs. 2 and 3 when the member 9 is withdrawn. If the material is not sufficiently resilient to resume the original position, it can be easily bent into the desiredform by a suitable step of operation e. g. by screwing into the coil the threaded shaft of a screw bolt the thread of which is of a shape and pitch according to the inner portions of the coil convolution. In most instances however, it will not be necessary to apply such additional step. If the material is of a kind generally used in coils here under consideration it will have a certain resiliency. In that event the length of the arc portion to be bent inwardly preparatory to being notched or recessed can be so selected and bending can, then, be accomplished so gradually that the bending stresses do not exceed the elastic limits. In consequence, the end convolution 2 will return of its own accord to its original position in relation to the subsequent convolution 4 when the member 9 is withdrawn.

As stated hereinbefore, it is also possible to shift the end convolution of the coil in a substantially axial rather than a radial direction in relation to the subsequent convolution in order to furnish suflicient space for the notching operation. This can 'be readily done in the manner illustrated in Fig. 4 where the edge of a wedgeshaped member 23 is pushed in the direction of the arrow between the end convolution 2| and the subsequent convolution 22 of a coil 20. In order to facilitate the application of member 23, it may be provided with a shoulder 24 for engagement of a portion of the circumference of the convolution 2|, and also in its top face, with a recess 25 which will be located underneath the notch 26 to be worked in the convolution 2i when the latter abuts against the shoulder 24. Thus, a cutting or punching tool 21 moved in the direction of the arrow d will be able to produce the desired notch. 28 in the convolution 2| without any danger of interference with the subsequent convolution 22, provided of course that the tool 2! is not moved beyond the bottom of the recess 25. When the notch or recess 26 has been shaped and tool 21 removed, member 23 may be withdrawn, whereupon convolution 2| may either be returned to its original position by a bending operation or it may be permitted to spring back owing to its inherent elasticity. The method illustrated in Fig. 4, is particularly well suited for mass production when member 23 is the stationary part of a machine and each coil to be notched is pushed against that member so that the edge of the wedge enters between the end convolution and the subsequent convolution.

It will be clear that the method according to my invention is applicable to coils of any desired wire cross-section and any notch or recess form to be produced. Furthermore, in a similar manner notches or recesses may be produced on the outer circumferential side of the end convolution as well as on the inner side. If this is desired, it is only necessary in the method illustrated in Fig. 3 to bend, prior to the notching step, the are 8 s0 far inwards that a portion of its outer periphery clears the inner periphery of the subsequent convolution, or to bend the end convolution outward rather than inward. If the method of Fig. 4 is used no change is required except for a provision of the recess 25 at a location close to the shoulder 24. It will also be understood that the method described is advantageously applicable if the coils to be recessed are wound with gaps between the convolutions and/or if the coils are of other than cylindrical e. g. conical shape.

Having now described several applications of my invention, it will be apparent to those skilled in the art that many alterations and modifications thereof may be made without departing from the spirit and essence of my invention,

which shall be limited only by the scope of the appended claims.

I claim:

1. A method of producing a substantially cylindrical wirecoil having anotch or recess on a peripheral side of one of its end convolutions which comprises winding a wir in a substantially cylindrical coil of desired shape, diameter and pitch of the finished product, bending an arc portion of the end convolution from its original position in relation to the subsequent convolution, workin a notch or recess of desired shape into said arc While holding it in the bent position, releasing said arc from hold and restoring its original position in relation to the subsequent convolution.

2. A method of providing a cylindrical wire coil with a notch or recess on a peripheral side of one of its end convolutions which comprises bending an arc portion of the end convolution from its original position in relation to the subsequent convolution, said are portion being selected so large that the bending stresses are within the elastic limits of the wire material, working a notch or recess of desired shape into said are while holding it in the bent position, and releasing said arc so as to permit it to spring back to its original shape and position.

3. A method of providin a cylindrical wire coil with a notch or recess on a peripheral side of one of its end convolutions which comprises bending an arc portion of the end convolution from its original position in relation to the subsequent convolution, supporting the so bent'portion against movement in axial direction towards the coil body, working a notch or recess of desired shape into the supported portion, separating the coil and the support from each other, and causing the bent portion to return to its original position.

4. A method of providing a cylindrical wire coil with a recess on a peripheral side of one of its end convolutions which comprises bending an arc portion of the end convolution in an axial direction away from the subsequent convolution, positioning a support for said bent portion between the latter and the subsequent convolution, working a notch or recess of desired shape in the supported portion, removing the support from between said end and subsequent convolutions, and causing the bent portion to return to its original position.

5. A method of providing a cylindrical wire coil with a notch or recess on a peripheral side of one of its end convolutions which comprises wedging a support between an arc portion of the end convolution and the subsequent convolution, working a notch or recess of desired shaped in said supported arc portion, removing said support from wedging position, and causing the bent portion to return to its original position.

6. A method of providing a cylindrical wire coil with a notch or recess on a peripheral side of one of its end convolutions which comprises pushing the coil in a substantially radial direction against the edge of a wedge so as to cause the latter to enter between an arc portion of the end convolution and the subsequent convolution, working a notch or a recess of desired shape in said portion of the end convolution, withdrawin said coil from said wedge, and causing said end convolution to return to its original position.

'I. A method as claimed in claim 6, wherein the length of said arc portion and the width of the gap between said portion and said second convolution caused by said wedging are so selected in relation to each other that the occurring bending stresses are within the elastic limits of the wire material, said end convolution being caused to spring back to its original position upon the withdrawal or the coil from said wedge.

8. A method of providing a cylindrical wire coil with a notch or recess on a peripheral side of one of its end convolutions which comprises bending an arc portion of the end convolution radially and progressively inward until the portion to be notched or recessed projects inwardly of the inner circumference of the coil body, supporting said are portion from the interior of the coil body while holding said portion in the bent position, working a notch or recess of desired shape in the inwardly projecting portion, removing the support, and restoring said arc portion to its original position.

9. A method of providing a cylindrical wire coil with a notch or recess on a peripheral side of one of its end convolutions which comprises bending an arc portion of the end convolution radially and progressively inward until the portion to be notched or recessed projects inwardly of the inner circumference of the coil body, said are portion being selected so large that the bending stresses are within the elastic limits of the wire material. supporting said arc portion from the interior of the coil body while holding said portion in the bent position, working a notch or recess of desired shape in the inwardly projecting portion, removing the support and permitting said are .portion to spring back to its original position.

o'r'ro HAAS. 

